package com.czc.lb;

import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.stereotype.Component;

import java.lang.annotation.Annotation;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

@Component
public class MyLB implements LoadBalancer {

    private AtomicInteger atomicInteger=new AtomicInteger();

    private final int getAndincrement(){
        int current;
        int next;
        do{
            current=this.atomicInteger.get();
            next = current>=2147483647 ? 0:current+1;
        }while (!this.atomicInteger.compareAndSet(current,next));//第一个参数是期望值,第二个参数是修改值

        System.out.println("*******第几次访问，次数next: "+next);
        return next;
    }

    //负载均衡算法:rest接口第几次请求数 % 服务器集群总数量=实际调用服务器位置下标 每次服务重启后rest接口计数从1开始
    @Override
    public ServiceInstance instances(List<ServiceInstance> serviceInstances) {
        int index=getAndincrement() % serviceInstances.size();
        return serviceInstances.get(index);
    }
}
